Microfilm reader and projection apparatus



H. L. GORDON Aug. 28, 1951 6 Sheets-Sheet 1 vENToR.

FTE.

Aug. 28, 1951 H. l.. GORDON 2,565,496

MICROEILM READER AND PROJECTION APPARATUS Filed Jan. 6, 1948 6 Sheets-Sheet 2 l 3 l. 3i i f' mnngllhlm 32 7 IRUN" 35 llg- 28, 1951 H. L.. GORDON 2,565,496

MICROFILM READER AND PROJECTION APPARATUS Filed Jan.. 6, 1948 6 SheecS-SheerI 5 .l g l s s g i l s y s n f I l l In L l. 8 7 s 6 l l s 1 l z s f l I i2 r i 1 E l i i I j i f n n j t INVENTOR. l 4

Aug. 28, 1951 H. GORDON 2,565,496

MICROFILM READER AND PROJECTION APPARATUS Filed Jan. e, 1948 6 Sheets-Sheet 4 INVENTOR Aug. 28, 1951 H. GORDON MIcRoPILM READER AND PROJECTION APPARATUS 6 Sheets-Sheet 5 Filed Jan. 6, 1948 Eff FIEl,l

)l Il Aug. 28, 1951 H. L.. GORDON MICROFILM READER AND PROJECTION APPARATUS 6 Sheets-Sheet 6 Filed Jan. 6, 1948 INVENTOR,

Patented Aug. 28, 1951 other.

MIRFILM READER AND PRorEcTIo ePlRTU w ...1. i, i d,

Herman L. Gordon, Silver Springglllld'. pplication January 6, 194g; Seria'l'Nlo.`

K'Ihis invention relates toA optical projection devices,` and more particularly to a portable apparatus for projecting enlarged images from a film s trip. e v Y A main object of the invention is to provide a novel and improved projecting apparatus for microfilm which is very simple in construction, easyto operate, and which may be reduced to' a relatively small bulk when not in use, thereby greatly facilitating storage of the apparatus or transportation thereof from place to place.

y, `A. further objectof ,the invention is to provide an. improved,.,micrommeeder whichl may be readily reducednt/o a compact size for transportationljorjstorage andI which may be manufactured atna` moderate `costeu fhereby it may be made more av ilable for general use in reading maktelfiel published lon microfilm than the relatively bulkyuandtexpensive devices now produced for this Rurnese-, y

A still. .further object of the invention is to prollfgvide Aan improved microfilm reader of the type which includes its own projection'screen but Whieh` readilyuadaptable for ywall projection cneccrlvcetionel externalfscreen- A still further .object of. the invention is coprovidewanimproved microlm reader which is light in uw ht, `ruggedinc onsrtuction, and which, by transposition ofwparts, mayV be reduced in bull; to Va' relatively,small package,'totally enclosing thehlenssystemand illumination means of the readerandmaffording aghighudegree of protection t th erertsof the.assembly. j e

4 "frstill.iurtherobject of the invention lis to provide an improved microfilmreader having a selfcontained, lorojection Y.screen and wherein the projec, tion Yportion of the reader may be e --rot'atedfrcufn a normal position ,with'respectjto lthemscreen nto a position ninety degrees on either side of said normal position to enable mcrollmvnaterial to be comfortably Yread on said ,s reen;,reg'fardlessl of the position in which it DrinedQnthelm, e

Al. still. furtherobjeetof `the invention isi to provide a microfilm readerhavingimproved lm feedingnclamping, Aandlrelease means, and also empf?, yingimproved. means for focussing the projection lensoi the. reader.. .l Y t A,

Further objects and advantages of the invention-willf-.beeome apparent` from the, following iption andclaims, and from the accompany v al. view. of a micr'of i ccordancewththe `present invention, said View showing the reader `Set up in operative position.

claims. (C1. sil-24) iii FigureLZ `is aj front elevational view;l partly in crossfsectionvof the microfilm' reader of Figure 1. Y Figure 3 is ajcross-sectional View taken on line Sei-'319i Figure 1.v Y l e s AFigurelY is a cross-sectional View taken on line 4-51 .offFgure 1. ,.4 l 1 Figure, 5 is a 'perspective view showing* the readerpf Figure 1 arranged for'transportation. vFigure is a tperspectiveview'of thesupporting baselelenlent ofthe .readerof Figure 1, also employeclas .the top vcover in Figuree5.

`ligure '1 is Aanelevational View, partlyin cross section, illustrating the manner in which the upper member-of the microfilm reader of Figure 1 isvtelescoped into the screen-enclosing housing oithel readerfwhen theapparatus is being collapsedrfortransportation or storage. i 'Figure 8 is an enlarged Vvdetail `cross-sectional vievv takenV on line 8'-8 of FigureBr Figure 9is an enlargedtcross-sectional detail view taken'on line g-fofFigure 8f:

jFigure 10 is `an enlarged detailelevationalvi'ew of a `reel`holdingclip employed in the microfilm rea'derof Figure 1. Y fj Figure 11 is -a side elevational" view of: a modiiied form of microfilm reader-according to the present invention, set-up for operation: Figure V12 is aperspectiveview of themicrofilm reader of Figure 11, in folded position for transportation or'storager Figure 13 is'an enlarged fragmentary vdetail view showing the sliding pivotalconnectionbe-y tween the top assembly and the-projection screen housing ofv the microfilm reader illustrated in Figuresileand Alim Y, s i Figure M is a fragmentary A'perspective view showing a 'portionl of the screen -housingemployed in the modification of-Figures-*l'l -and 12;

'Figure 15 is anenlarge'd cross-sectional detail View `taken on line I 5-| 510i Figure 1-1:

Referring to :the *idrawingsrand' more fpartcularly to Figures -1to 4',- I'l designates a housing made of sheet meta-lornthe likeywhichis preferably square in horizontal section andewhich has" vertical side `walls l2, l2,-a Vertical-rear wall I--3, and a bottonrwall |4,'whichfis suitably coatedgwith light diffusing material or' isotherwisewcovered;` as V'by a white paper orfabric sheet",

vto provide aj projection screen: The front 'of the'houssingis open so-thatthe bottom wall of the housing Vmaybe v iewedi from the qfront thereof; The top lwall ofthe housing comprises a'plate I5, 'shown inliigure 7, fformedwithA a large centrai aperture I8-, the plate-l 5-being Isecured to housing at a level slighty below the plane of the top edges of said side and rear walls. The front edge of plate I5 is formed with a Vertical ange I9 whose top edge is ush with the top edges of the side and rear walls, thereby defining a square seat indicated at 20 in Figure 7.

As shown in Figures 5 and '1, housing I I forms the main outer casing of the instrument when it is collapsed for transportation or storage.

The bottom wall I4 of the housing is formed at its front edge with a vertical flange 2i which is forwardly offset with respect to the plane of the open front of the housing, for a purpose Which will be subsequently described.

Secured to and depending from the bottom wall I4 adjacent the corners thereof are supporting feet 22. Designated at 23 is a square pan which forms a bottom support for housing I I and which also serves as the top cover for the instrument when it is collapsed for transportation or storage. The rear wall of cover 23, designated at 24 is of substantially greater height than the front wall, shown at 25, thereof, whereby the top wall 26 of the cover slopes forwardly and downwardly, as shown in Figure 1. Said top wall 26 is formed with depressions or recesses 21 adjacent its corners, said depressions or recesses being adapted to receive the feet 22 of housing II to prevent said housing from sliding downwardly from the supported position thereof shown in Figure 1. The housing I I is thus supported in a forwardly tilted position, whereby the bottom screen-carrying wall I4 is inclined upwardly and rearwardly, facilitating the observation of the screen through the open front portion of the housing.

Removably supported on the square seat 20 is a top assembly, indicated generally at 28, which carries the main optical elements of the instrument, as will be shortly described. Assembly 28 comprises a hollow rear columnar housing 29 extending substantially for the full lateral width of the assembly 28 and having a rear wall whose top end rises a short distance above the plane of the top edges of the columnar rear housing 29, as shown at 30. The top end of the housing 29 is open. Secured in housing 29 are vertical partitions 3I, 3I, which divide the housing into end compartments 32, 32 adapted to receive microfilm reels and the like, and a center compartment 33 adapted to receive miscellaneous objects such as spare bulbs and the like, for storage purposes.

The rear wall of housing 29 is formed with laterally projecting vertical end anges 34, 34 which are bent forwardly and are offset laterally slightly beyond the planes of the side walls I2, I2 of the main supporting housing for a purpose to be presenty described.

Secured rigidly to the lower portion of the rear columnar housing 29 and coextensive in lateral width with said rear housing 29 is a subhousing 35 which, together with the lower portion of rear housing 29, defines a square base for the assembly 28 adapted to lit into the square seat 20. The bottom of sub-housing 35 is open.

Secured to the top wall of sub-housing 35 and communicating with the interior thereof is a cylindrical casing 36 which is perpendicular to said top wall of the sub-housing and whose axis is substantially centered with respect to the square seat 20. Casing 35 is formed with an inclined slot 31, preferably at its front surface. Telescoped inside casing 36 and freely slidable therein is a cylindrical tube 38 in which is secured a plate 39. Centrally secured to the plate 39 is a lens barrel 40 which carries the projection lens 4I. Threaded into tube 38 and passing through the slot 31 is a shouldered thumbscrew 42. When thumbscrew 42 is loosened, it may be employed to rotate tube 38 inside the sleeve 36, the slot 31 acting on the shank of the thumbscrew as a cam to move tube 38 axially inside sleeve 38. Projection lens 4I may thus be moved to a focusing position and locked in said position by tightening the thumbscrew 42.

Overlying the top end of sleeve 36 is a plate member 43 formed with a depending rear flange 44 which is rigidly secured to the front wall of the columnar housing 29, as by welding, or 'the like. Plate member 43 is formed with a rectangular aperture 45 which is axially aligned with the projection lens 4I. Secured to said plate member 43 over the aperture 45 is a transparent glass plate 46.

Pivotally secured to the rear portion of plate member 43 by a transverse hinge 41 is an upstanding plate member 48. Secured to the upper portion of plate member 48 is an angle bracket 49 having a forwardly projecting arm 56. Secured to said arm 56 is a bracket 5I 'to which is secured the lamp socket 52. A projection lamp 53 is received in socket 52, said socket being so located that the lamp filament is substantially in axial alignment with the projection lens 4I. Secured to the lower portion of plate member 48 is a flanged forwardly projecting plate member 54. Plate member 54 is formed with an aperture 55 over which is secured a first condenser lens 56, the aperture and lens being axially aligned with the lamp and lens system defined by lamp 53 and lens 4I. Secured to said plate member 54 over the condenser lens 56 is an inverted U-shaped bracket 51 whose top arm is formed with an aperture 58. Secured to said top arm and underlying the aperture 58 is a second condenser lens 59, said second condenser lens and aperture 58 being also in axial alignment with the aforementioned lamp and projection lens system.

Secured to the bottom surface of plate member 54 and depending therefrom are parallel plate members 66 and 6I extending in planes normal to the plane of plate 48 and spaced symmetrically on each side of the axis of the lens system. Pivotally secured to said plate members respectively at 62 and 63 for rotation around a transverse axis is a anged rectangular frame member 64 formed with a rectangular aperture 65 which is substantially in registry with the rectangular aperture 45 of the plate member 43. Secured to the bottom of frame member 64 under the aperture 65 is a transparent glass plate 66. An elongated bar member 61 is secured to plate member 6I) a short distance above the adjacent flange edge of frame member 64 to limit pivotal rotation of said frame member.

Secured to the front wall of the columnar rear housing 29 at 61 is the lower end of an upwardly extending leaf spring 68, the tcp end of said spring bearing against the upper portion of the hinged plate 48 to bias said hinged plate forwardly, whereby glass plate 68 exerts pressure downwardly on glass plate 46. The pivotal connections at 62 and 63 allow the frame member 64 to automatically assume a position wherein plane surface contact of glass plate 66 with a film resting on glass plate 46 may be obtained. The spring 68 provides sufficient force to atten out said film, whereby any possible aberration due to curvature of the film surface is eliminated.

attempt The pressurev on the film, however, is not'su'flloient to prevent the film fromV being 4vdrawn between the glass plates during `the operation of the reader.

Designated at 69, is a housing whose 'forward wal-l portion is detachably secured to' the flange of plate member 54 by means of a thumbscrew 10' passing through an aperture in said forward wall portion and threaded into "said flange. The housing j65) is provided at its rear vportion with inturned flanges 'H which vengage themar'gi'nal portions 'of upstanding platel member 4B. When the thumbscrew 'I0 is extracted, the housing V69 may be removed by moving it upwardly with respect to plate member 48 until the 'inturne'd flanges 1l are clear of said plate member. k'Illis permits replacement of the projection bulb Awhen required.

Secured to the front wall of columnar housing 29 adjacent the housing 69 isa bracket 12 'formedwith a transversely extending forward arm 13. Secured to housing 69 is an angle bracket 14 having a laterally projecting arm l5 which is substantially parallel to but forwardly spaced from arm '13. aperture in arm and is threaded into arm 13. By tightening said thumbscrew the lamp housing 69 and the supporting plate members 54 and 48 may be rotated rearwardly to raise glass plate 66 a suicient distance above glass plate 46 to permit film to be freely inserted therebetween, as when a new fllm strip istoV be read, or to be freely removed from between said glass plates whenever required.

The side edges of the housing 69 are formed with shallow notches, such as shown at 11, slightly greater than rllm width, to provide clearance for film passing transversely between the glass plates 46 and 66 during normal operation of the4 reader. Saidnotches a'ct as guides to prevent forward or rearward movement of the l'ilm strip as it moves between theglass plates.

Secured to the top wall of sub-housing at each side of the sleeve member 36 is a resilient U-shaped reel bracket 18, the brackets 'I8 being in transverse alignment with the notches 11 and with the film clamping plates 46 and 66. The rear arm '19 of each bracket is substantially greater in height than the front arm 80 thereof. Secured to the intermediate portion of the rear arm is a bearing stud Bl, and rotatably received in the front arm 80 is a stud 82 having an en larged squared inner head portion 63. Secured to the shank of stud 82 is a knob 84. A conventional fllmreel, shown in dotted view at 85 in Figure 10, is receivable within each bracket 18, the rear bore portion of the reel receiving the bearing stud BI and being rotatable thereon and the front squared bore portion of the reel interlocking with the squared stud head 83. The reel may therefore be rotated by rotating knob 84. `To remove the reel the rear arm 19 of' the bracket is sprung rearwardly; moving the bearing stud 8l out of the rear bore portion of the reel and allow# ing the reel to be readily disengaged from the squared stud head 83. A new reel may be inserted in' the bracket by a reverse procedure.

When thel reader is to be employed for wall projection, the top assembly 28, carrying the main optical elements and the film supporting elements of the instrument is supported on any suitable base, such as a table or the like, with therear columnar housing 29 positioned hori-A zontally or at a slight incline and resting onv the base supportv employed. The pari'Z' may A 'thumbscrew 16 passes through an CIV 6. be' placed beneathtlie columnar 'housing to provide the desired tilted 'positionof 'the instrument, so that thepro'ject'ion axis" thereof will be paral-v rel to the inclined top wall n2t f thal pan, the columnar housing 29 being supported on `said tawall 2s. l l

Since 'the top assembly 28 is sduare in plan at its lower portion and 'is 'no'rn'ially supported in the' square seat 20 'a manner allowing said top assembly tol be readily lifted out 'of said seat, it ls 'merely necessary to raise said top assembly dat of seatl 2n, 'votata said top' assembly n inety degrees., 'aridrfeplace thewtop assembly in "S'et 2U. This 'enables I`I1`l 5 -lll1 material printed 4'trail/SVl"`S"e1y nslld V'ltally th strip tobe read fromA the normal frontal position of observation. 'l a when thereader 'to be collap'sj='.-e for transpgrtauon ar storage, the top `asslemlaly ai ls lifted but flcs *seat '2ty and telescope@ into' the bottom housing' ll through the Screen Viewing opening 'thereof `in the manner illustrated in FigureA 7. when the assembly 2:1 is fully housed in bottom housing H1, the bottomvedge of the back Wall' f 'ellllnnar housing 2S vis received inside the oifs'et flange 2| and the front vertical edges of the side wal1's12, lI 2 are received inside the oiiset vertical flanges 34, N34. ln this posi'- tion of assembly 28, the top edge of the rear wall of said assembly is" flush with the top edges or the Walls 'of the housing Il; The pan 2? is then telescop'd vover the t'o'p of these parts. Secured t'o the upper intermediate portions of the side walls I2, I2 of the mainhousing H are eonventional latches 86, 36, preferably of nieuwe belt type, which; areLA adapted to engage' over lugl'elemeats s1, t1 carriedy by the' side flanges of pan 2%.H When thepan is locked to the' bottom housing Il by the'Y interengagement of latchesv', 66 with the lug elements 8 1, Si,

all of the parts Il, 28 and23a`re Arigidly secured in interlocking relation, as yillustrated in Figure 5.

`Pan y23 is provided with avhandle 88 pivotally secured to its to'p wall, by means of which the collapsed unit may be readily carried from place to place.

Referring now' to Figures llv to l5, a modiiied1 form of microlm reader according to the present invention is illustrated, wherein Il' designates a generally rectangular housing having a bottom wall I4 which is suitably coated with a flat white material ordis lined with other suitable screen material such as white blotting paper or the like. Housing H' has side walls I2",

i2 and a rear wall I3 but is open at its front.

'Ihe front edge of bottomlwall I4, is formed with an' upstanding flange 2l which is slightly forwardly oliset with respect to the front plane of the housing. The top portions of side walls I2', I2 are formed with horizontal slots 89, 8,9 which extend substantially for the full width of said side walls and terminate in downwardly directed vertical portions 96, inwardly adjacent the rear wall I3. rDesignated at 28 is a top assembly which carries the same optical elements and is substantially the same in construction as thetop assembly 28 of the previously described embodimentvof the invention. TopA assembly 28" lits snugly in `thetop portion ci housing IVI' and has secured` to its lower f crward corners laterally projecting headed pins 6l which are respectively slidably received in the horizontal slots 89,v 89 formed in the heusinggside walls l2', I'2.l andsupport the front' ene of top assembly 2a'. secured' tul the row-'er marginal portion of the rear Wall of top assembly 28 is a horizontal angle bar 92 which bears on the top edge of the rear wall I3 of housing ll and supports the rear end of said top assembly.

In the operative position of the microfilm reader, screen housing Il is supported in a forwardly inclined position on the top wall of a cover pan 23', substantially ,the same in construction as the cover pan 23 of the previously described embodiment of the invention. Figure ll shows the relative positions of the parts when the reader is set up for operation.

When the microfilm reader is to be collapsed for transportation or storage, top assembly 28 is rotated counter-clockwise on its pivot pins 9|, as viewed in Figure 11, and is telescoped inwardly into housing Il from the dotted position shown in Figure l1 until the rear wall of top assembly 28 clears the flange 2|. At this time the pivot pins 9| reach the vertical slot portions 9G and allow the top assembly to descend inwardly of the iiange 2l. The cover 23' is then placed over the top of housing Il and is latched thereto as in the previously described embodiment of the invention. The side flanges of pan 23 are formed with vertical slots 93, providing clearance for the heads of pins 9| when said pan is iitted on the top of housing Il' as above described. The side iianges 34, 34 of top assembly 28 interlock with the front edges of side walls l2', I2 in the same manner as in the previously described embodiment of the invention.

While certain specific embodiments of a microfilm reader have been disclosed in the foregoing description, it will be understood that various modiications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

l. A microfilm reader comprising a screen housing, a lm projection unit adapted to be supported on the top of said screen housing, said screen housing being formed with a screen viewing opening through which said film projection unit may at times be telescoped into said screen housing, a cover member adapted to be placed over the screen housing when the projection unit is telescoped therein, said lm projection unit having a wall portion whose top end abuts the side surface of the top end of the housing when the lm projection unit is received within the housing, and means on said cover member engageable with the top end of the wall portion of said iilm projection unit to prevent Withdrawal of said projection unit from its telescoped position in the screen housing.

2.. A microlrn reader comprising a rectangular housing square in plan provided at its bottom wall with a projection screen, one of the side walls of said housing being formed with a large opening through which said screen may be observed, said housing having upstanding projections at the marginal portions of its top wall dening a square seat, said top wall ybeing formed at its intermediate portion with an aperture, a lm projection unit having a square base snugly receivable in said seat with its projection axis extending through said aperture and intercepted by said screen, said lm projection unit being at times receivable through said opening into said housing, said film projection unit having a wall portion whose top end abuts the side surface of the top end of the housing when the film projection unit is received within the housing, and a flanged cover fitting over the top ends of the housing and said wall portion and acting to retain said lm projection unit in telescoped position within said housing.

3. The structure of claim 2, and wherein the` side flanges of said cover have parallel bottom edges which are inclined with respect to the top of the cover, whereby said cover may be employed as an inclined support for the screen housing.

4. The structure of claim 2, and wherein said projection unit is provided with flanges interlocking with the front edges of the side walls of the screen housing when the projection unit is in telescoped position within said screen housing.

5. A microfilm reader comprising a main housing having a viewing screen at its bottom wall, a top member provided with a lm projection unit, means on said main housing for supporting the top member thereon with said projection unit directed toward said viewing screen, a viewing opening being formed in one of the side walls of the main housing and the top member being at times receivable through said viewing opening into housed position in said main housing, and upstanding fiange means carried by said main housing at the lower` margin of said viewing opening and engaging said top member to lock said top member against outward movement with respect to said main housing when said top member is in housed position.

6. A microfilm reader comprising a main housing having a viewing screen at its bottom wall, a top member provided with a film projection unit, means on said main housing for supporting the top member thereon with said projection unit directed toward said viewing screen, a viewing opening being formed in one of the side walls of the main housing and top member lbeing at times receivable through said viewing opening into housed position in said main housing, upstanding ange means carried by said main housing at the lower margin of said viewing opening and engaging said top member to lock said top member against outward movement with respect to said main housing when said top member is in housed position, said top member having a wall portion whose top end abuts the side surface of the top end of the main housing when said top member is received within the main housing, and a cover member fitting the top of said main housing and over the top and of said wall portion and acting to restrain said top member against upward movement in said main housing.

'7. A microfilm reader comprising a main housing having a viewing screen at its bottom wail, a top member slidably and pivotally secured to said main housing and carrying a film projection unit, means on said main housing for suuporting the top member thereon with said projection unit directed toward said viewing screen, the housing being formed with a viewing opening at one of its walls and the top member being at times receivable through the viewing opening for movement into housed position within said main housing, and a flanged cover fitting over said main housing and engageable with said top member when it is in housed position to restrain the top member against outward movement from said housed position.

8. A microfilm reader comprising a screen housing substantially open at its front Wall, a film projection unit, means on said housing for supporting the projection unit thereon with the projection unit directed toward the bottom wall of said housing, the lm projection unit being at times receivable through said substantially open front wall and being rearwardly movable into telescoped position in said housing, said projection unit having a wall portion whose top end lies laterally adjacent the side of the top end of the housing when said projection unit is received Within the housing, and a flanged cover fitting over the top of said housing and over the top end of said wall portion, thereby engaging the projection unit when it is in telescoped position in said housing to restrain upward and outward movement of said projection unit with respect to said housing.

9. A microfilm reader comprising a screen housing substantially open at its front wall, a lm projection unit, means on said housing for supporting said projection unit thereon with the projection unit directed toward the bottom wall of the housing, the film projection unit being at times receivable through said substantially open front Wall and being rearwardly movable into telescoped position in said housing, side flanges carried by said film projection unit receiving the forward vertical edges of the housing when said unit is in telescoped position, an upwardly projecting front iiange carried by the bottom wall of the housing engageable with the projection unit to restrain said unit from outward movement from its telescoped position, said projection unit having a wall portion Whose top end lies laterally adjacent the side plane of the top end of the housing when said projection unit is received Within the housing, and a flanged cover fitting over the top of the housing and over the top end of said wall portion, thereby engaging said projection unit when it is in housed position to restrain it from upward and outward movement with respect to the housing.

l0. A microfilm reader comprising a main housing member having a viewing screen at its bottom wall, a top member, one of said members being formed at its sides with opposed horizontal slots and the other member being provided with pin elements slidably and pivotally received in said slots, a lm projection unit mounted on said top member, and means on said main housing member formed and arranged to support said top member thereon with said projection unit directed toward said viewing screen, the housing member being formed with a viewing opening at its front wall and the top member being at times receivable through said viewing opening for horizontal movement into housed position within said main housing member.

HERMAN L. GORDON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,172,945 Cook Feb. 22, 1916 1,653,743 Stegmann Dec. 27, 1927 2,008,982 Hopkins July 23, 1935 2,221,160 Worthington et al. Nov. 12, 1940 2,268,450 Haggett Dec. 30, 1941 2,279,463 Hopkins Apr. 14, 1942 2,369,248 Pratt Feb. 13, 1945 2,377,476 Berglund June 5, 1945 FOREIGN PATENTS Number Country Date 862,028, France Nov. 22, 1940 

